Newt Gingrich, the first candidate to campaign in Delaware, came here Monday night pushing his $2.50-per-gallon-of-gas energy plan and jabbing President Obama about comments caught on an open microphone with outgoing Russian President Dmitri Medvedev.

Gingrich said that Obama's suggestion that he would have more flexibility to negotiate on nuclear arms after winning the 2012 election, was "destructive of American interests."

"This is a president who is amazingly destructive of American interests, something by the way of which we were reminded of today, when he didn't know there was an open microphone," he said to meeting of local Republican groups.

"He promises the Russian president as soon as he gets the election out of the way, he'll sell out the American missile defense system. They need to give him a little 'space' so he can be flexible right after the election. I think this is a really alarming behavior and it makes me want to know how many other countries has he promised things after the election, if they'll, quote, 'give him a little space.' What does that tell us about the Iranians or North Koreans."

Gingrich continued to push the idea of $2.50-a-gallon gasoline as the signature platform of his campaign here. He attacked Obama for sidetracking the Keystone XL Pipeline as a means to help political ally Warren Buffet.

"If you build [the pipeline] for the Canadians, you also then can carry North Dakota oil. Today they have to ship it in a railroad owned by Warren Buffett. So you may wonder what some of the pressure is for not completing the pipeline," he said to applause.

"If gasoline continues to go up, [Obama] can't buy enough ads to convince the American people that it is cheap," he said.